The present invention relates to a thread traversing device for winding units.
For winding of threads with extremely high thread speeds, for example 6,000 m/min. thread traversing devices are known in which the thread is reciprocated by drivers mounted on two belt runs which move near one another in opposite directions. The alternating movement of the threads is therefore actuated not as in conventional thread traversing devices by a single reciprocating thread guide, but instead, the oppositely moving drivers alternatingly engage and guide the threads. Since the drivers on the reverse points of the threads are neither accelerated nor decelerated, the influence of the inertia mass of the thread guiding elements during the thread reverse is completely eliminated.
German reference DE-OS 1,535,091 shows a different belt thread traversing device. In several embodiments two endless belts running over two guiding rollers are arranged so that a run of one belt is guided at a short distance parallel to a run of the other belt. There are also examples in which the guiding rollers of one belt and the guiding rollers of the other belt are arranged on coaxial or parallel offset axes near one another. In other words, they are arranged so that the guiding rollers of one belt and the corresponding guiding rollers of the other belt face one another at a side surface. It has been shown in practice that in the two-belt systems, due to different expansion of both belts as a result of different material properties or different aging, sychronization problems often occur which can lead to an inaccurate formation of the end surfaces of the coil. The novelty of the present invention has nothing to do with such two-belt systems.
In another embodiment disclosed in this patent only a single running belt is provided. It forms one longer run between two outer guiding rollers and another shorter run of the traversing region between inner guiding rollers. All guiding rollers lie in one plane and in a row one behind the other when seen in the movement direction of one run. The outer guiding rollers are arranged at relatively great distance from one another. Each inner roller is arranged in the intermediate space between both outer driving rollers close to the same The inner guiding rollers guide the short run over a path which substantially corresponds to the axial distance of both inner guiding rollers and defines the maximum possible traversing stroke, in short distance parallel to the longer run moving in opposite direction. During transition from the outer guiding rollers to the associated inner guiding rollers the run of the belt is approximately S-shaped so that the belt abuts with its side surface against the outer guiding roller and with its another side surface against the inner guiding roller. The drivers are arranged on a small edge of the belt.
German document DE-OS 3,627,544 describes a belt traversing with a single belt guided over outer and inner guiding rollers. They are arranged similarly to the device described hereinabove. However, the belt is guided between outer guiding rollers and associated inner guiding rollers in form of a reverse loop over an additional deviating roller. All roller axes are parallel, so that the belt runs in one plane as described in the preceding device. This plane extends parallel to the traversing triangle.
A device disclosed in U.S. Pat. No. 3,333,782 differs from the above mentioned device by the fact that the axes of different rollers are slightly inclined relative to one another. As a result the both runs of the traversing region extend not exactly parallel, but intersect under a very acute angle. Thereby the transition of the thread is facilitated at the end of the traversing region. This arrangement however does not differ in that the arrangement is provided with four guiding rollers as considered in the movement direction of one of the runs, arranged substantially in a row one behind the other. The belt stands on edge with respect to the plane of the traversing triangle, and the drivers are arranged on a small edge of the belt. The belt abuts with its one side surface against the outer guiding roller and with its another side surface on the associated inner guiding roller.
In the above discussed belt traversing device in which both oppositely running runs belong to a single endless belt, the traversing stroke or in other words the coil length is evidently not greater than the path over which the both runs run parallel or approximately parallel near one another. This path is equal to the axial distance of both inner guiding rollers or in other words the shorter run defines the traversing stroke. This means in other words that the structural length of the belt traversing device or in other words the size in the traversing direction always exceed the spool length by at least three times the roller diameter. When several such systems are arranged for simultaneous binding of several spools located on one axle in a row near one another, the system-dependent distance between each two coils is always greater than the three-times roller diameter. The roller diameter cannot be selected arbitrarily small. The minimal permissible roller diameter depends on the type of the belt and is prescribed by the belt manufacturer. In the praxis, the belt traversing device which pertains to the prior art has considerably great structural length and respective coil distances as in traversing device which are for example provided with turn threaded shafts.
German reference DE-OS 3,739,850 deals with the above mentioned problem and discloses a traversing device in which two guiding rollers are arranged at both ends of the traversing region with parallel axes in a plane and are mirror symmetrical relative to one another. Therefore, both runs which pass the traversing region have the same length. Each of the rollers is associated in a laterally arranged deviating roller. The belt is guided over both deviating rollers in a loop-type manner, and the part of the belt connected with both deviating rollers is guided at a small distance before or after both guiding rollers. The total run of the belt lies in one plane, In this device the ratio of structural length to traversing stroke is substantially better than in other belt systems. It has however the disadvantage that it is very bulky in direction transverse, to the traversing movement in a plane parallel to the traversing triangle. Thereby its possibilities of utilization are limited and the main advantage cannot be materialized for structural reasons.